• Title/Summary/Keyword: ARRAY

Search Result 9,432, Processing Time 0.045 seconds

Electrical Stimulation Parameters in Normal and Degenerate Rabbit Retina (정상 망막과 변성 망막을 위한 전기자극 파라미터)

  • Jin, Gye-Hwan;Goo, Yong-Sook
    • Progress in Medical Physics
    • /
    • v.19 no.1
    • /
    • pp.73-79
    • /
    • 2008
  • Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa (RP) or age related macular degeneration (AMD). Recently Korean consortium launched for developing retinal prosthesis. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we performed voltage stimulation experiment both in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: $50k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. Mono-polar electrical stimulation was applied through one of the 60 MEA channel, and the remaining channels were used for recording. The electrical stimulus was a constant voltage, charge-balanced biphasic, anodic-first square wave pulse without interphase delay, and 50 trains of pulse was applied with a period of 2 sec. Different electrical stimuli were applied. First, pulse amplitude was varied (voltage: $0.5{\sim}3.0V$). Second, pulse duration was varied $(100{\sim}1,200{\mu}s)$. Evoked responses were analyzed by PSTH from averaged data with 50 trials. Charge density was calculated with Ohm's and Coulomb's law. In normal retina, by varying the pulse amplitude from 0.5 to 3V with fixed duration of $500{\mu}s$, the threshold level for reliable ganglion cell response was found at 1.5V. The calculated threshold of charge density was $2.123mC/cm^2$. By varying the pulse duration from 100 to $1,200{\mu}s$ with fixed amplitude of 2V, the threshold level was found at $300{\mu}s$. The calculated threhold of charge density was $1.698mC/cm^2$. Even after the block of ON-pathway with L-(1)-2-amino-4-phosphonobutyric acid (APB), electrical stimulus evoked ganglion cell activities. In this APB-induced degenerate retina, by varying the pulse duration from 100 to $1200{\mu}s$ with fixed voltage of 2 V, the threshold level was found at $300{\mu}s$, which is the same with normal retina. More experiment with APB-induced degenerate retina is needed to make a clear comparison of threshold of charge density between normal and degenerate retina.

  • PDF

Comparison of Retinal Waveform between Normal and rd/rd Mouse (정상 마우스와 rd/rd 마우스의 망막파형 비교)

  • Ye, Jang-Hee;Seo, Je-Hoon;Goo, Yong-Sook
    • Progress in Medical Physics
    • /
    • v.19 no.3
    • /
    • pp.157-163
    • /
    • 2008
  • Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa or age-related macular degeneration. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we investigated differences of the retinal waveforms in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: 50 $k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. In normal mice (C57BL/6J strain) of postnatal day 28, only short duration (<2 ms) retinal spikes were recorded. In rd/rd mice (C3H/HeJ strain), besides normal spikes, waveform with longer duration (~100 ms), the slow wave component was recorded. We attempted to understand the mechanism of this slow wave component in degenerate retina using various synaptic blockers. We suggest that stronger glutamatergic input from bipolar cell to the ganglion cell in rd/rd mouse than normal mouse contributes the most to this slow wave component. Out of many degenerative changes, we favor elimination of the inhibitory horizontal input to bipolar cells as a main contributor for a relatively stronger input from bipolar cell to ganglion cell in rd/rd mouse.

  • PDF

Identification of Flavonoids from Extracts of Opuntia ficus-indica var. saboten and Content Determination of Marker Components Using HPLC-PDA (손바닥선인장 추출물의 플라보노이드 구조 규명 및 HPLC-PDA를 이용한 지표성분의 함량 분석)

  • Park, Seungbae;Kang, Dong Hyeon;Jin, Changbae;Kim, Hyoung Ja
    • Journal of the Korean Society of Food Science and Nutrition
    • /
    • v.46 no.2
    • /
    • pp.210-219
    • /
    • 2017
  • This study aimed to establish an optimal extraction process and high-performance liquid chromatography (HPLC)-photodiode array (PDA) analytical method for determination of marker compounds, dihydrokaempferol (DHK) and 3-O-methylquercetin (3-MeQ), as a part of materials standardization for the development of health functional foods from stems of Opuntia ficus-indica var. saboten (OFS). The quantitative determination method of marker compounds was optimized by HPLC analysis, and the correlation coefficient for the calibration curve showed very good linearity. The HPLC-PDA method was applied successfully to quantification of marker compounds in OFS after validation of the method in terms of linearity, accuracy, and precision. Ethanolic extracts from stems of O. ficus-indica var. saboten (OFSEs) were evaluated by reflux extraction at 70 and $80^{\circ}C$ with 50, 70, and 80% ethanol for 3, 4, 5, and 6 h. Among OFSEs, OFS70E at $80^{\circ}C$ showed the highest contents of DHK and 3-MeQ of $26.42{\pm}0.65$ and $3.88{\pm}0.29mg/OFS100g$, respectively. Furthermore, OFSEs were determined for their antioxidant activities by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation (LPO) inhibitory activities in rat liver homogenate. OFS70E at $70^{\circ}C$ showed the most potent antioxidant activities with $IC_{50}$ values of $1.19{\pm}0.11$ and $0.89{\pm}0.09mg/mL$ in the DPPH radical scavenging and LPO inhibitory assays, respectively. To identify active components of OFS, various chromatographic separation of OFS70E led to isolation of 11 flavonoids: dihydrokaempferol, dihydroquercetin, 3-O-methylquercetin, quercetin, isorhamnetin 3-O-glucoside, isorhamnetin 3-O-galactoside, narcissin, kaempferol 7-O-glucoside, quercetin 3-O-galactoside, isorhamnetin, and kaempferol 3-O-rutinoside. The results suggest that standardization of DHK in OFSEs using HPLC-PDA analysis would be an acceptable method for the development of health functional foods.

Monte Carlo Simulations of Detection Efficiency and Position Resolution of NaI(TI)-PMT Detector used in Small Gamma Camera (소형 감마카메라 제작에 사용되는 NaI(TI)- 광전자증배관 검출기의 민감도와 위치 분해능 특성 연구를 위한 몬테카를로 시뮬레이션)

  • Kim, Jong-Ho;Choi, Yong;Kim, Jun-Young;Im, Ki-Chun;Kim, Sang-Eun;Choi, Yeon-Sung;Joo, Kwan-Sik;Kim, Young-Jin;Kim, Byung-Tae
    • Progress in Medical Physics
    • /
    • v.8 no.2
    • /
    • pp.67-76
    • /
    • 1997
  • We studied optical behavior of scintillation light generated in NaI(TI) crystal using Monte Carlo simulation method. The simulation was performed for the model of NaI(TI) scintillator (size: 60 mm ${\times}$ 60 mm ${\times}$ 6 mm) using an optical tracking code. The sensitivity as a function of surface treatment (Ground, Polished, Metal-0.95RC, Polished-0.98RC, Painted- 0.98RC) of the incident surface of the scintillator was compared. The effects of NaI(TI) scintillator thickness and the refractive index of light guide optically coupling between the NaI(TI) scintillator and photomultiplier tube (PMT) were simulated. We also evaluated intrinsic position resolution of the system by calculating the spread of scintillation light generated. The sensitivities of the system having the surface treatment of Ground, Polished, Metal-0.95RC, Polished-0.98RC and Painted-0.98RC were 70.9%, 73.9%, 78.6%, 80.1% and 85.2%, respectively, and the surface treatment of Painted-0.98RC allowed the highest sensitivity. As increasing the thickness of scintillation crystal and light guide, the sensitivity of the system was decreased. As the refractive index of light guide increases, the sensitivity was increased. The intrinsic position resolution of the system was estimated to be 1.2 mm in horizontal and vertical directions. In this study, the performance of NaI(TI)-PMT detector system was evaluated using Monte Carlo simulation. Based on the results, we concluded that the NaI(TI)-PMT detector array is a favorable configuration for small gamma camera imaging breast tumor using Tc-99m labeled radiopharmaceuticals.

  • PDF

Evaluation of 3DVH Software for the Patient Dose Analysis in TomoTherapy (토모테라피 환자 치료 선량 분석을 위한 3DVH 프로그램 평가)

  • Song, Ju-Young;Kim, Yong-Hyeob;Jeong, Jae-Uk;Yoon, Mee Sun;Ahn, Sung-Ja;Chung, Woong-Ki;Nam, Taek-Keun
    • Progress in Medical Physics
    • /
    • v.26 no.4
    • /
    • pp.201-207
    • /
    • 2015
  • The new function of 3DVH software for dose calculation inside the patient undergoing TomoTherapy treatment by applying the measured data obtained by ArcCHECK was recently released. In this study, the dosimetric accuracy of 3DVH for the TomoTherapy DQA process was evaluated by the comparison of measured dose distribution with the dose calculated using 3DVH. The 2D diode detector array MapCHECK phantom was used for the TomoTherapy planning of virtual patient and for the measurement of the compared dose. The average pass rate of gamma evaluation between the measured dose in the MapCHECK phantom and the recalculated dose in 3DVH was $92.6{\pm}3.5%$, and the error was greater than the average pass rate, $99.0{\pm}1.2%$, in the gamma evaluation results with the dose calculated in TomoTherapy planning system. The error was also greater than that in the gamma evaluation results in the RapidArc analysis, which showed the average pass rate of $99.3{\pm}0.9%$. The evaluated accuracy of 3DVH software for TomoTherapy DQA process in this study seemed to have some uncertainty for the clinical use. It is recommended to perform a proper analysis before using the 3DVH software for dose recalculation of the patient in the TomoTherapy DQA process considering the initial application stage in clinical use.

Association of Single Nucleotide Polymorphisms in the Prostaglandin-endoperoxide Synthase 2 (PTGS2) and Phospholipase A2 Group IIA (PLA2G2A) Genes with Susceptibility to Esophageal Squamous Cell Carcinoma

  • Liu, Fen;Wei, Wen-Qiang;Cormier, Robert T.;Zhang, Shu-Tian;Qiao, You-Lin;Li, Xin-Qing;Zhu, Sheng-Tao;Zhai, Yan-Chun;Peng, Xiao-Xia;Yan, Yu-Xiang;Wu, Li-Juan;He, Dian;He, Yan
    • Asian Pacific Journal of Cancer Prevention
    • /
    • v.15 no.4
    • /
    • pp.1797-1802
    • /
    • 2014
  • Background: The prostaglandin-endoperoxide synthase 2 (PTGS2) and phospholipase A2 group IIA (PLA2G2A) genes encode enzymes that are involved in arachidonic acid and prostaglandin biosynthesis. Dysregulation of both genes is associated with inflammation and carcinogenesis, including esophageal squamous cell carcinoma (ESCC). We therefore hypothesized that there is an association between single nucleotide polymorphisms (SNPs) in these genes and susceptibility to ESCC. Methods: We performed a gene-wide tag SNP-based association study to examine the association of SNPs in PTGS2 and PLA2G2A with ESCC in 269 patients and 269 healthy controls from Taihangshan Mountain, Henan and Hebei Provinces, the rural area of China which has the highest incidence of esophageal cancer in the world. Thirteen tag SNPs in PLA2G2A and 4 functional SNPs in PTGS2 were selected and genotyped using a high-throughput Mass Array genotyping platform. Results: We found a modest increased risk of ESCC in subjects with the PTGS2 rs12042763 AA genotype (OR=1.23; 95% CI, 1.00-3.04) compared with genotype GG. For PLA2G2A, a decreased risk of ESCC was observed in subjects with the rs11677 CT (OR=0.51, 95%CI, 0.29-0.85) or TT genotype (OR=0.51, 95%CI, 0.17-0.96) or the T carriers (CT+TT) (OR=0.52, 95%CI, 0.31-0.85) when compared with the CC genotype. Also for PLA2G2A, rs2236771 C allele carriers were more frequent in the control group (P=0.02). Subjects with the GC (OR=0.55, 95%CI, 0.33-0.93) or CC genotype (OR=0.38, 95% CI, 0.16-0.94) or the C carriers (GC+CC) (OR=0.52, 95%CI, 0.32-0.85) showed a negative association with ESCC susceptibility. Conclusions: Our results suggest that PTGS2 and PLA2G2A gene polymorphisms may modify the risk of ESCC development.

Disease Progression from Chronic Hepatitis C to Cirrhosis and Hepatocellular Carcinoma is Associated with Increasing DNA Promoter Methylation

  • Zekri, Abd El-Rahman Nabawy;Nassar, Auhood Abdel-Monem;El-Rouby, Mahmoud Nour El-Din;Shousha, Hend Ibrahim;Barakat, Ahmed Barakat;El-Desouky, Eman Desouky;Zayed, Naglaa Ali;Ahmed, Ola Sayed;Youssef, Amira Salah El-Din;Kaseb, Ahmed Omar;El-Aziz, Ashraf Omar Abd;Bahnassy, Abeer Ahmed
    • Asian Pacific Journal of Cancer Prevention
    • /
    • v.14 no.11
    • /
    • pp.6721-6726
    • /
    • 2013
  • Background: Changes in DNA methylation patterns are believed to be early events in hepatocarcinogenesis. A better understanding of methylation states and how they correlate with disease progression will aid in finding potential strategies for early detection of HCC. The aim of our study was to analyze the methylation frequency of tumor suppressor genes, P14, P15, and P73, and a mismatch repair gene (O6MGMT) in HCV related chronic liver disease and HCC to identify candidate epigenetic biomarkers for HCC prediction. Materials and Methods: 516 Egyptian patients with HCV-related liver disease were recruited from Kasr Alaini multidisciplinary HCC clinic from April 2010 to January 2012. Subjects were divided into 4 different clinically defined groups - HCC group (n=208), liver cirrhosis group (n=108), chronic hepatitis C group (n=100), and control group (n=100) - to analyze the methylation status of the target genes in patient plasma using EpiTect Methyl qPCR Array technology. Methylation was considered to be hypermethylated if >10% and/or intermediately methylated if >60%. Results: In our series, a significant difference in the hypermethylation status of all studied genes was noted within the different stages of chronic liver disease and ultimately HCC. Hypermethylation of the P14 gene was detected in 100/208 (48.1%), 52/108 (48.1%), 16/100 (16%) and 8/100 (8%) among HCC, liver cirrhosis, chronic hepatitis and control groups, respectively, with a statistically significant difference between the studied groups (p-value 0.008). We also detected P15 hypermethylation in 92/208 (44.2%), 36/108 (33.3%), 20/100 (20%) and 4/100 (4%), respectively (p-value 0.006). In addition, hypermethylation of P73 was detected in 136/208 (65.4%), 72/108 (66.7%), 32/100 (32%) and 4/100 (4%) (p-value <0.001). Also, we detected O6MGMT hypermethylation in 84/208 (40.4%), 60/108 (55.3%), 20/100 (20%) and 4/100 (4%), respectively (p value <0.001. Conclusions: The epigenetic changes observed in this study indicate that HCC tumors exhibit specific DNA methylation signatures with potential clinical applications in diagnosis and prognosis. In addition, methylation frequency could be used to monitor whether a patient with chronic hepatitis C is likely to progress to liver cirrhosis or even HCC. We can conclude that methylation processes are not just early events in hepatocarcinogenesis but accumulate with progression to cancer.

Analysis of Image Distortion on Magnetic Resonance Diffusion Weighted Imaging

  • Cho, Ah Rang;Lee, Hae Kag;Yoo, Heung Joon;Park, Cheol-Soo
    • Journal of Magnetics
    • /
    • v.20 no.4
    • /
    • pp.381-386
    • /
    • 2015
  • The purpose of this study is to improve diagnostic efficiency of clinical study by setting up guidelines for more precise examination with a comparative analysis of signal intensity and image distortion depending on the location of X axial of object when performing magnetic resonance diffusion weighted imaging (MR DWI) examination. We arranged the self-produced phantom with a 45 mm of interval from the core of 44 regent bottles that have a 16 mm of external diameter and 55 mm of height, and were placed in 4 rows and 11 columns in an acrylic box. We also filled up water and margarine to portrait the fat. We used 3T Skyra and 18 Channel Body array coil. We also obtained the coronal image with the direction of RL (right to left) by using scan slice thinkness 3 mm, slice gap: 0mm, field of view (FOV): $450{\times}450mm^2$, repetition time (TR): 5000 ms, echo time (TE): 73/118 ms, Matrix: $126{\times}126$, slice number: 15, scan time: 9 min 45sec, number of excitations (NEX): 3, phase encoding as a diffusion-weighted imaging parameter. In order to scan, we set b-value to $0s/mm^2$, $400s/mm^2$, and $1,400s/mm^2$, and obtained T2 fat saturation image. Then we did a comparative analysis on the differences between image distortion and signal intensity depending on the location of X axial based on iso-center of patient's table. We used "Image J" as a comparative analysis programme, and used SPSS v18.0 as a statistic programme. There was not much difference between image distortion and signal intensity on fat and water from T2 fat saturation image. But, the average value depends on the location of X axial was statistically significant (p < 0.05). From DWI image, when b-value was 0 and 400, there was no significant difference up to $2^{nd}$ columns right to left from the core of patient's table, however, there was a decline in signal intensity and image distortion from the $3^{rd}$ columns and they started to decrease rapidly at the $4^{th}$ columns. When b-value was 1,400, there was not much difference between the $1^{st}$ row right to left from the core of patient's table, however, image distortion started to appear from the $2^{nd}$ columns with no change in signal intensity, the signal was getting decreased from the $3^{rd}$ columns, and both signal intensity and image distortion started to get decreased rapidly. At this moment, the reagent bottles from outside out of 11 reagent bottles were not verified from the image, and only 9 reagent bottles were verified. However, it was not possible to verify anything from the $5^{th}$ columns. But, the average value depends on the location of X axial was statistically significant. On T2 FS image, there was a significant decline in image distortion and signal intensity over 180mm from the core of patient's table. On diffusion-weighted image, there was a significant decline in image distortion and signal intensity over 90 mm, and they became unverifiable over 180 mm. Therefore, we should make an image that has a diagnostic value from examinations that are hard to locate patient's position.

Population Size Estimation of the Kaloula borealis in the Daemyung Retarding Basin (대명유수지에 서식하는 맹꽁이 Kaloula borealis 개체군 크기 추정)

  • Choi, Seo-Young;Rho, Paikho
    • Korean Journal of Environment and Ecology
    • /
    • v.30 no.4
    • /
    • pp.684-693
    • /
    • 2016
  • Daemyung retarding basin located near the confluence floodplain of the Nakdong and Kumho River is a large spawning site for the endangered Kaloula borealis, and needs for protecting the habitat of the endangered species are increasing. However, scientific studies are rarely conducted on the population characteristics and ecological knowledge on the species in the basin. This paper aims to estimate the population size and spatial distribution of the species that inhabited at the Daemyung retarding basin, using the capture-recapture method. Also, pitfall traps were installed in each habitat types classified with micro-topographic features, slope aspects, and vegetation communities to identify the spatial distribution characteristics of the Kaloula borealis of each habitat in the retarding basin. Field survey on the species was conducted from May 2013 to October 2014, showing that the species emerged in May, became more active during July and August and started to hibernate at the end of October. Using capture-recapture method, the first survey was carried out from July to August, 2014. Ninety-eight toads were captured, marked, and released back into the site. In the second survey, 68 toads including 5 marked toads of the previous survey were captured. Based on these two-sample surveys, around 535-2,131 individual toads are estimated to inhabit the Daemyung retarding basin. Fifty-seven pitfall traps were installed in four habitat types: mounded and vegetated flatland, lowland swamps, and slope areas of both the southern and western parts of the basin in order to delineate spatial abundance of the endangered Kaloula borealis during the rainy season when the species is actively spawning. Pitfall traps at the spatially explicit array indicated that the species gradually move to the slope areas near the Daemyung stream, showing high occurrence density of the Kaloula borealis compared to the lowland swamps after the spawning season. The emergence of Kaloula borealis in the lowland swamps appeared to be comparatively higher during the spawning season. However, after the spawning season the toads species rapidly moved into the neighboring land of relatively high elevation such as the slope area towards the Dalsung protected wetlands and Daemyung River. These results are closely related to the migration patterns that toads tend to return to the sheltering sites and/or hibernating grounds after the spawning season. Also, the Kaloula borealis moved to the nearest high-level vegetated areas as the lowland swamps of their spawning grounds deteriorated with the expansion of permanent ponds due to the rise in the groundwater level.

Development of a Method for Analyzing the Nicotine Content in Synthetic Flavoring Substances as Unauthorized E-cigarette Liquid by Using HPLC (전자담배 액상 충진제와 유사한 합성착향료 중 니코틴의 HPLC 분석법 개발)

  • Kim, Jae-Young;Lee, Sang-Mok;Chang, Moon-Ik;Cho, Yoon-Jae;Lee, Han-Jin;Chae, Young-Sik;Rhee, Gyu-Sik
    • Korean Journal of Food Science and Technology
    • /
    • v.45 no.6
    • /
    • pp.693-699
    • /
    • 2013
  • A simple, sensitive, and specific method for quantifying the nicotine content of synthetic favoring substances (SFS) was developed using high performance liquid chromatography (HPLC) with a photo-diode array detector (PDA). Nicotine was extracted from SFS samples by using an acid-base liquid-liquid extraction method with dichloromethane and distilled water. The nicotine content was quantified by HPLC/PDA (261.9 nm) with a $C_{18}$ column under a gradient of 10% acetonitrile with 20 mM ammonium formate (ammonia solution adjusted to pH 8.7) to 100% acetonitrile. The calibration curve, analyzed from concentration standards between 0.1 to 2 mg/L, presented linearity with a correlation coefficient ($r^2$)>0.9999. The limit of quantitation (LOQ) of nicotine in SFS was 0.4 mg/kg, and the average recoveries ranged from 76.4% to 96.3%. The repeatability of measurements, expressed as the coefficient of variation (CV%), ranged from 1.74 to 5.12%. This newly developed method for nicotine quantification in SFS can be considered an analytical method with an acceptable level of sensitivity and repeatability.